An optional router.
If provided, in dev mode, will be used to display more debug information when a handler can't be found.
This is a lazy parameter, to avoid circular dependency issues, since the router may well depend on
this.

An optional router.
If provided, in dev mode, will be used to display more debug information when a handler can't be found.
This is a lazy parameter, to avoid circular dependency issues, since the router may well depend on
this.

By default, the implementation of this method delegates to onProdServerError when in prod mode, and
onDevServerError in dev mode. It is recommended, if you want Play's debug info on the error page in dev
mode, that you override onProdServerError instead of this method.